Porcelain coated substrate and process for making same

ABSTRACT

The present invention provides for a sign consisting of an alloy substrate encapsulated in a porcelain coating which can be selectively applied to different areas of the substrate. The coating provides a smooth transitional region on graphic indicia of the sign to make the sign impervious to vandalism, fire and dirt. There is also provided a process of selectively applying a second coat of porcelain to the existing coating to only those elevated portions elevated or Braille portions of the substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/008,324 filed Dec. 7, 1995 pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to signs with surface relief, and inparticular to signs encapsulated in a fired porcelainized enamel coatingwhich is weather and vandal resistant.

2. Description of the Related Art

Substrates, signs and methods of producing the same are disclosed in thefollowing patents:

    ______________________________________    U.S. Pat. No.       Inventor(s)    ______________________________________    2,353,019           Dyer    2,581,310           Sweo    3,726,707           Prosser, et al.    3,961,112           Genevitz, et al.    4,074,010           Knight    4,075,049           Wood    4,084,032           Pasersky    4,225,908           Small, Jr.    5,084,309           Smith, et al.    5,091,224           Kushida, et al.    5,098,813           Nakano, et al.    5,162,160           Matsui, et al.    5,196,395           James, et al.    5,389,413           Condon, et al.    5,534,347           Chen, et al.    ______________________________________

U.S. Pat. No. 2,353,019 to Dyer, discloses a method of etching steel,wherein steel sheets are dipped in ferric sulfate etching bath so thatthe sheet is prepared for a coating such as electroplating, enameling orother ornamental surfacing, such as tin or terne coatings.

U.S. Pat. No. 2,581,310 to Sweo, discloses a porcelain enamel articleand method of producing same, wherein a surface of a steel work piece iscleaned and roughened to provide deep sharp edged pits therein, picklingin nitric acid after which a cover coat of porcelain enamel is appliedto the roughened surface.

U.S. Pat. No. 3,726,707 to Prosser, et al., discloses porcelainenameling of steel, wherein nickel, cobalt and cooper are electrolesslydeposited on steel after which enameling frit is coated to the steel.

U.S. Pat. No. 3,961,112 to Genevitz, et al., discloses luminousembossable tape which consists of a strippable two piece backing layer,a layer of adhesive adjacent thereto and a luminous layer which may bemixed and combined with the adhesive layer.

U.S. Pat. No. 4,074,010 to Knight, discloses ceramic-paint coatingswherein a material in finely divided form is applied as a first coat ofceramic paint, the coating is cured without fusing the ceramic paint,and then a second coat of ceramic paint is applied after which curing isdone without paint. Curing is done at 750° F. or lower and therefore,the paint is not a fused coating.

U.S. Pat. No. 4,075,049 to Wood, discloses a method of preparingretroreflective sheeting wherein a monolayer of glass spheres isdisposed to provide pathways therebetween for flow of a resinousmaterial in the pathways to link a film over the spheres with a filmbeneath the spheres to which the spheres are adhered and partiallyimbedded.

U.S. Pat. No. 4,084,032 to Pasersky, discloses a process for making hotstamping foil for producing textured surface effects consisting of acarrier sheet, a releasing lacquer coat applied to the carrier sheet, anopaque color coat applied to said releasing lacquer coat and aheat/pressure activatable resinous adhesive coat applied to said opaquecolor coat.

U.S. Pat. No. 4,225,908 to Small, Jr., discloses a lighting fixture andglass enclosure having high angle anti-reflective film, wherein theanti-reflective film is produced by a chemical etch/leach process whichis porous and skeletonized, and has a high silica content.

U.S. Pat. No. 5,084,309 to Smith, et al. discloses a product presentingdifferent artistic images in the presence and absence of ambient lightand a fabrication method therefor, wherein a primary image is producedas a plurality of first image forming elements on a substrate, afterwhich a substantially clear phosphorescent material overlays the primaryimage to create a secondary image as a plurality of second image formingelements. The primary image is visible in ambient light and thesecondary image is visible in the absence of ambient light.

U.S. Pat. No. 5,091,224 to Kushida, et al. discloses a method ofpreparation of a surface-coated, metal-made ornamental articleconsisting of coating a metalica substrate with a glassy protectingcoating to prevent blooming or whitening on the surface.

U.S. Pat. No. 5,098,813 to Nakano, et al., discloses astimulable-phosphor radiation image storage panel using specified heator heat and activator-containing gas treatment.

U.S. Pat. No. 5,162,160 to Matsui, et al., discloses a fluorescentscreen consisting of a substrate formed of a fibrous light-scatteringmaterial and a filling mixture of an organic fluorescent substance, anda binder evenly disbursed within said fibrous light-scattering material.

U.S. Pat. No. 5,196,395 to James, et al., discloses a method forproducing crystallographic boundary junctions in oxide superconductingthin films, wherein V-shaped grooves are etched on a face of a crystalsubstrate by anisotropic etchant.

U.S. Pat. No. 5,389,413 to Condon, et al., discloses three dimensionalsignage and a method of making same, consisting of a thermoplasticlaminate, preferably transparent, with a sign face layer ofthermo-plastics, a visual character adhered to the layer, a backgroundcolor layer adhered to the layer, and a 3-D character in registrationwith an adhered to the background color layer.

U.S. Pat. No. 5,534,347 to Chen et al., discloses a fusing roll have afluorocarbon-silicone barrier layer consisting of a cylindrical corecoated with a layer of silicone elastomer upon which is coated acomposition cured by heating the mixture for such to be cured.

Among the patents discussed above, there is no disclosure of signageconsisting of a substrate having surface relief, such as relieflettering and/or Braille characters integrally formed from thesubstrate, and being encapsulated in fixed porcelain enamel anotherporcelain is selectively depositedto the relief lettering and/or Braillecharacters to provide a visual contrast between areas of relief and theunderlying substrate, wherein the specifications of height, width,slope, spacing, and necessary ratios between such parameters comply withthe Americans with Disabilities Act (of 1991 and 1992) as amended(hereinafter ADA).

It should be noted that among the visually impaired, approximately tenpercent (10%) of such persons are able to read and understand Braille,while the remaining 90% rely on what is commonly referred to as "lettertracing". This is the impetus to produce signage with both relieflettering and Braille characters. Signage using this surface relief mustcomply with the ADA requirements which state in part " . . . letters andnumbers shall have a width to height ratio between 3:5 and 1:1 and astroke-to-height ratio between 1:5 and 1:10. Character height, as sizedaccording to the viewing distance . . . 0.032" raised lettering not lessthan 5/8" height, no higher than 2"; and symbols in their own 6" highfield and accompanied with Grade II Braille. Braille dot diameter0.059", inter-dot spacing 0.090", horizontal separation between cells0.241", vertical separation between cells 0.395". Characters andbackground of sign shall be an eggshell or matte (non-glare) finish.Characters shall meet a minimum 70% contrast to background."

The ADA specifically requires that with respect to signage, the alphanumerical text and symbols printed on the signs must be formed thereonto comply with certain size and viewing distance requirements. Inparticular, the text and characters must be in relief, i.e. projectingfrom the surface of the sign, in order to comply with the ADA. Thisconstruction and arrangement enables those with limited eyesight todiscern or finger trace the sign and the messages conveyed, as well asenable the blind to read Braille characters of the sign.

It would therefore be advantageous to have a process of producing a signwith surface relief which complies with the ADA specifications and isprotected from the weather, harmful chemicals and vandalism.

In addition, such a process should provide a sign which is easy to cleanand maintain.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to provide a process of makinga sign so that an exterior surface of the sign is resistant to wear,alteration and/or destruction.

It is another object of the present invention to provide a process forproducing relief indicia and symbols on a sign, wherein the indicia isin different grades of relief at different areas on an exterior surfaceof the sign.

It is another object of the present invention to provide a sign which iseasy to clean, inexpensive to maintain, and which protects the exteriorsurface and structural integrity of the sign.

It is another object of the present invention to provide a process fortreating an exterior surface of the sign to be of a reflective qualityranging from matte to glossy (specular.

It is another object of the present invention to provide a sign whichhas non-glare porcelainized metal based relief indicia thereon, as wellas on the background.

It is another object of the present invention to utilize recyclablemanufacturing materials for the sign.

It is another object of the present invention to provide a processwherein the exterior surface of the sign is uniformly treated so thatthe exterior surface of the relief indicia share a common exteriorsurface.

It is another object of the present invention to provide an exteriorsurface of a sign to display letters, numerals, symbols, designs, wordsand/or Braille characters (dots), including Grade I and/or II Brailletranslation, in relief.

It is another object of the present invention to provide Braillecharacters and relief lettering over the surface of the sign to meet therequirements and specifications by the ADA.

It is another object of the present invention to provide relief portionsof the sign with an ability to glow in reduced light conditions, by aninfusion of phosphorescent pigments that are contained in a porcelaincoating of the invention, wherein the sign that has been charged withsunlight or fluorescent light will glow and be readable for up toapproximately eight hours.

It is another object of the present invention to provide a process forencapsulating an alloy substrate of the sign, which process deposits thecoating on the substrate to a particular thickness at select areas ofthe substrate.

It is another object of the present invention to provide a method ofselectively coating relief portions of the sign such that elevatedportions are easily distinguishable from the underlying surface area ofthe sign.

It is another object of the present invention to provide a process forencapsulating an alloy substrate for a sign with a porcelain coatinghave phosphorescent pigments to glow during reduced ambient lightconditions.

It is another object of the present invention to provide a sign whichincludes gently sloping transition regions on at least the porcelaincoating at an area where the raised letters, symbols or Braillecharacters extend from the surface of the substrate.

It is still another object of the present invention to provide aprotective coating for signage, which protective coating substantiallyreduces if not eliminates sharp, angular regions on the sign surfacewhich might otherwise trap debris to foul the Braille characters andcause pitting of the sign.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, referencemay be had to the detailed description of the preferred embodimentstaken in conjunction with the accompanying drawings, of which:

FIG. 1 is a top plan view of a sign treated according to the presentinvention;

FIG. 2 is a cross-sectional view of the sign of the present inventiontaken through line 2--2 in FIG. 1;

FIG. 3 is a partial cross-section side view of the substrate coated toprovide surface relief thereon; and

FIG. 4 is a flow chart showing the steps of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, the present invention is a sign 10consisting of an extremely durable substrate 12, in sheet or plate form,so that the sign obtains the advantages and fulfills the objectsdescribed above. To that end, the substrate 12 of the present inventionis composed of an approved low-carbon steel, brass, bronze, copper,aluminum, cold rolled steel, other compatible alloys or combinationsthereof. The substrate 12 includes an upper surface 14, a lower surface16 and a sidewall 18 interconnecting the upper surface 14 and the lowersurface 16. The upper surface 14, lower surface 16 and sidewall 18 arereferred to herein collectively as "the exterior surface" of thesubstrate 12. The material of the substrate 12 is capable of retaining aprotective coating, such as a non-metallic inorganic fused coating 20 offired porcelainized enamel with the substrate, sheet, plate, orfabrication having a thickness ranging from approximately 0.005" to 24"thick/deep.

The matte or specular (glossy) porcelain enamel coating 20 covers theexterior surface of the substrate 12 or envelopes the substrate as asubstantially vitreous (or glossy), inorganic coating bonded to themetal substrate utilizing a fusion method above approximately 1,000degrees fahrenheit (1,000° F.) and up to 1,650° F. The porcelain surfaceis uniformly deposited, finished and free of defects that mightotherwise effect the serviceability of the sign, or detract from thegeneral appearance of the product when viewed from a distance of fivefeet (5'), or the distance from which the product is viewed, whicheveris greater. The total thickness of the porcelain coating isapproximately 0.007 inches to approximately 0.020 inches on the exteriorsurface of the substrate 12 including the edges of the substrate, ifsuch an application is necessary. In those instances where thespecifications require more than one color to achieve graphicrequirements these parameters can be adjusted.

The varying degrees of specular finish of the porcelain enamel coatingcan range from matte to full gloss, and covers the display surface andall sides, edges of the sign. The coating 20 envelopes the substrate 12as a substantially vitreous (or glossy), inorganic coating bonded to thesubstrate utilizing fusion.

The process according to the present invention produces signage whichhas surface relief in the form of relief words, letters, numerals,symbols such as that shown at 22 and Braille characters (dots) such asthat shown at 24. The process also provides for subsequent layering offire porcelainized enamel in contrasting colors so that a word, symbol,etc., such as that shown at 26 is displayed on the porcelainizedcoating. In addition, the protective coating 20 of porcelain is disposedon the substrate such that a sloping transition surface 26 is providedin a region where the protective coating 20 covers the substrate wherethe protruding surface relief and/or Braille characters extend from thesubstrate 12.

The process of the present invention to produce the substrate isdiscussed below with reference also to FIGS. 2-4.

Contrasting surface lettering coloring is selectively applied to therelief graphics by either one or a combination of the following methods:

Hand application using brayers.

Hand application using brushes and a flexible palette knife.

Machine application using rollers.

Silk screen method.

Photo-stencil method.

Hand-cut stencil.

Contrasting lettering and graphics are applied to the flat surfaces byeither one or a combination of the following methods:

Photo-stenciling.

Hand-cut stenciling.

Silk screen method.

The coating of contrasting color on the surface of the relief lettersand graphics is also porcelain enamel which is bonded to the firstporcelain enamel coating utilizing a fusion method at temperatures to1,650 degrees Fahrenheit (1,650° F).

The first step is to provide a substrate of one of the alloys discussedabove. The alloy is formed by cutting into a predetermined shapedepending upon its application as signage in the environment to be used.The substrate is also edge-detailed, i.e. beveled, and corner detailed,i.e. radiused and scalloped. Sanding, polishing and/or de-burring canalso be performed on the substrate 12 if necessary.

The substrate is then encapsulated within a photo-sensitive resist 28.The resist 28 extends over the exterior surface of the substrate 12 andpermitted to cure to maximize adhesion to the substrate.

A "photo-tool" 30 is disposed over the surface of the substrate 12 forwhich surface relief is to be effected, such as shown in FIG. 4. Thephoto-tool 30 is preferably an acetate sheet or template having athickness of preferably 0.005", although other thicknesses can beemployed. The acetate sheet 30 has regions of film positive (+) and filmnegative (-) formed therein as shown in FIG. 4. For example, the areadesignated 30a is a black or negative film which prevents ultraviolet(UV) light 32 from reaching the underlying resist 28. That is, the filmnegative portion 30a is opaque so that the layer of resist 28 on thesubstrate 12 immediately beneath the film negative portion is shieldedfrom the UV rays.

The acetate sheet 30 is also provided with clear regions designated 30bwhich are substantially transparent to permit the UV rays frompenetrating the acetate sheet 30 and impacting on the resist 28immediately beneath the regions 30b. The regions 30b are referred to asthe film positive regions and permit the UV rays to impact on the resist28, such that the UV polymerizes the resist 28 to the surface of thesubstrate immediately beneath the resist 28.

Alternatively, the acetate sheet 30 can be disposed on the resist 28 ina vacuum so that a tight interface is established between the resist 28and the acetate sheet 30. The vacuum will in effect cause the acetatesheet 30 to be "drawn down" onto the resist 28 so that there is no spacetherebetween in which UV light could inadvertently enter and polymerizean area where polymerization is not to occur.

The substrate 12 is then exposed to a photo-developer wash, for example,immersed in an agitated, heat and pH controlled photo developer wash toweaken and sluff-off the unpolymerized resist background. The portionsof the resist 28 which will be stuffed off are those portions of theresist 28 immediately beneath the acetate sheet regions 30a and beneaththe diaper or cloak 32. The polymerized resist is impervious to thephotodeveloper acid wash. Therefore, after the substrate 12 has beenwashed, the resist remains polymerized to those portions immediatelybeneath the film positive regions 30b.

The substrate is then subjected to acid etching which employs controlledheat, agitation and pH controls to etch away background 34 of thesubstrate 12 that has not been polymerized so that surface relief isprovided on the substrate.

Photo-Chemical or Electro-Chemical Acid Etching

Using a photographically sensitive resist which is applied to the metalsubstrate, the image is exposed and developed using a film positive ornegative which contains the graphics to be reproduced, the resistedmaterial is then put in an etching (acid) bath for etching away themetal to a controlled depth as required for the job. In the case of ADA(Americans with Disabilities Act) signage, the etch is to a depth of0.03125". The panel is then cleaned, pre-treated, primed and porcelainenamelized to create a ceramic coating.

EDM--Electro-Discharge Machining

An electromechanical process of metal removal from selected areas. Theareas not removed are controlled by computer generated compatible fileformats that drive the CAD based machine to do its work. The metal isthen sent through the porcelain process (see specs. attached).

Machine or Raster Engraving Method

If manual, by a milling machine, if computer controlled then using a CNCmachine that mils, cuts or routes away the unwanted metal through amechanical cutting process. The remaining bottom area are then smoothedout through a series of abrasives to remove the cutting or routing linesthat are left behind.

Stamping/Embossing

This method utilizes a male and female die set that is used to raise thespecific areas or letters and Braille that need to be raised. The dieset is required for each different message or lettering that is needed.This method is geared toward higher volume repeats of the same image.The plates are then sent for the enameling process.

Next, any remaining resist on the substrate is stripped away. Theresulting relief surface on the substrate 12 includes the tactilesurface areas of relief lettering 22 and/or Braille characters 24 due tothe surface relief being effected and represented by 36, which is alsoshown in FIG. 2.

The entire substrate 12 is then encapsulated in a protective coating 38of porcelain. The porcelain coating 20 is fused to the substrate 12 atup to 1,650 degrees Fahrenheit (1,650° F.) depending upon the substratealloy used and colors selected for the porcelain. This results in asubstrate having surface relief with the relief text, Braille charactersextending from the surface of the substrate. However, at this stage,there is not discernible difference between the colors of the relieftext and Braille characters and the remaining surface area of thesubstrate.

The sloping, smooth, transition surface 26 eliminates right angles wherethe relief indicia extends from the top surface 14 of the substrate 12,so that debris or other matter does not become trapped on the surface ofthe substrate and impair the visibility or reflective qualities of thesubstrate. In addition, because foreign matter does not easily adhere tothe sign, there is less chance that blind persons using the Braillecharacters will misinterpret a character due to some inadvertentlytrapped material between the Braille characters.

The smooth transition surface provides for easy cleaning of the surfaceof the sign and deflects objects which might otherwise become trapped onthe sign. The smooth transition surface 26 also is more comfortable tofinger trace.

Selected portions 38 of the coating 20 are then coated with acontrasting color so that the text is discernible to the general publicand those that are visually impaired, but not blind. Of course, theBraille characters do not have to have any contrasting color but thiscan be done. The selective porcelainization of the relief characters isdone at a fusing temperature up to 1,650 degrees (1,650° F.) which willfuse the second porcelain coating 38 with the first porcelain coating20.

Finally, the substrate is permitted to cool so that the porcelaincoatings can cure.

The result of the process of the present invention is that the reliefbetween and among the indicia and Braille characters still meets thespecifications of the ADA as pertains to height, width, slope, andspacing between characters.

In addition, as shown in FIG. 1, relief text 22 and the Braillecharacters 24 as dots do not extend from the underlying surface at 90°angles, which would result in sharp edges irritable to the touch andcapable of snagging objects. Instead, there is a gentle transitionalslope region 26 in the coating 20 where the lettering and the charactersextend from the underlying surface to their selected height.

The deposition of the coatings 20,38 is substantially uniform so thatthe relief text and Braile characters extend to a similar height abovethe substrate. The graphics are reproduced in conformity with standardsfor Braille and Tactile lettering as specified by the ADA.

The face of the letters can have a matte, satin or spectral finish, asmay the background as well.

Recessed background areas are colored with a 70% contrast to theletters, when conformity to ADA specifications is required; otherwiseany color combinations of background or letters and symbols may be used.

The materials described above for the signage can be color matched tocomply with the particular application and to conform with areaaesthetics, the corners contoured, (i.e. radius, scallop, specialshapes, etc.), and the edges treated, (i.e. bevel, quarter-round, customdetails, etc.). The signage surface can display raised copy, Braillecharacters with raised or recessed symbols/indicia, or combinationthereof.

The glassy finish on the substrate surface is practically impervious toattack, particularly the surface areas having Braille or other raisedindicia. However the ADA requires that a glossy (or specular) exteriorsurface cannot be employed because it is indistinguishable andpractically invisible to a person who, although not blind, is visuallyimpaired, i.e. the glossy surface makes it extremely difficult, if notimpossible, for a visually impaired individual to read the signagebecause of the high reflection and the reduced contrast between theraised surfaces and relief of the signage.

The sign of the present invention is extremely resistant to cutting,acid, fire, alkalines, etc.

It will be understood that the embodiments described herein are merelyexemplary and that a person skilled in the art may make many variationsand modifications without departing from the spirit and scope of theinvention. All such variations and modifications are intended to beincluded in the scope of the invention as defined by the appendedclaims.

What is claimed is:
 1. A method for making a sign, comprising the stepsof:selecting an alloy substrate from which the sign is to be formed;cutting the alloy substrate to a predetermined shape; beveling the edgesof the alloy substrate; scalloping the corners of the alloy substrate;removing grease and other foreign matter from a surface area of thealloy substrate; encapsulating the alloy substrate in a photo-resist;curing the photo resist; covering select portions of the photo-resist;simultaneously exposing select portions of the photo-resist;simultaneously providing a pressure differential to the alloy substrate;exposing the photo-resist to ultraviolet (UV) light; polymerizing thephoto-resist exposed to UV light; removing the unpolymerizedphoto-resist; etching exposed surface area of the alloy substrate notcovered by the photo-resist to a selected depth; removing thepolymerized photo-resist; encapsulating the alloy substrate in aporcelain coating; heating the alloy substrate to a temperature up toapproximately 1,650° F.; and cooling the alloy substrate.
 2. A method ofmaking a sign, comprising the steps of encapsulating an alloy substratein a photo-resist;covering selective portions of the photo-resist;exposing the photo-resist to ultraviolet (UV) light to polymerizeexposed portions of the photo-resist to the underlying substrate;removing portions of the photo-resist not exposed to the UV light;etching areas of the alloy substrate under the photo-resist earlierremoved; encapsulating the alloy substrate in a protective coating ofporcelain enamel.
 3. The method according to claim 2, wherein the stepof exposing the photo-resist to UV light comprises:subjecting the alloysubstrate to a pressure differential.
 4. The method according to claim2, further comprising the step of:selectively applying another porcelaincoating to portions of the alloy substrate elevated above the underlyingsurface of the alloy substrate.
 5. A method of making a sign, comprisingthe steps of:forming an alloy substrate to a predetermined size;positioning the alloy substrate for a machining operation; selectinggraphic indicia to be displayed at a surface of the alloy substrate;removing portions of the surface of the alloy substrate such thatremaining portions of the alloy substrate display the graphic indicia inrelief; lubricating the alloy substrate with a lubricant; sandblastingthe alloy substrate; roughening an upper surface of the graphic indicia;encapsulating the alloy substrate in a porcelain coating; and heatingthe porcelain coating to a select temperature to fuse the porcelaincoating to the alloy substrate.
 6. The method according to claim 5,further comprising the step of:disposing another porcelain coating atselect areas along the upper surface of the graphicindicia.
 7. A methodof making a sign, comprising the steps of:forming an alloy substrate toa predetermined size; disposing said alloy substrate in a press;pressing portions of one side of the alloy substrate toward an oppositeside of the alloy substrate to extend the portions out of the oppositesides to a select distance from the opposite side of the alloysubstrate; cleaning the alloy substrate; and encapsulating the alloysubstrate in porcelain.